I'm working on a 2004 Mercury Grand Marquis. The blower motor has suddenly stopped working. All speeds were available and it was blowing cold air before the malfunction. It was blowing fine, shutdown, sat overnight, and the blower would not come on after it was started the next day. This vehicle is equipped with the temperature control option for the climate controls.

I've checked the fuses and relays, they're good. The fuses are intact and the relay was swapped with a known good unit.

Is there anything else to check before getting out the multimeter? I'd suspect the blower resistor, except the fan is not even working on high.

Update 1

I've been cruising the forums, sounds like it might be the fan controller (present when equipped with automatic temperature control, in the same location the resistor would be otherwise). It's under the hood on the passenger side, on the firewall under two heater hoses which have to come off to get at it, to the right of the blower motor itself if you're facing towards the rear of the vehicle.

Update 2

There was no ground on the blower motor connector, which indicated a bad blower speed control module. Module replaced with the redesigned part. Blower now works.

just had that part no. 8W7Z-19E624-A replaced by mercury dealer part cost 170.77 .fixed my problem, but was supprized by the cost vice the resistor cost of manual system.would like to know cost of same controller purchased elswhere?
–
user4703Mar 18 '14 at 16:15

@j.keller You can get it through various wholesale parts sources in the US for around $77 plus shipping. I got it from a dealer parts department I've done a lot of business with for a cash discount. I can't remember the exact price, but I think it was more than wholesale and less than you paid, probably around $100 (no shipping). I had it in my hands within 24 hours, too, which was an important consideration.
–
Mark Johnson♦Mar 18 '14 at 17:47

2 Answers
2

If you can get at the blower motor turn it on and put your hand on to see if you can feel the motor running. You may be able to feel it try to start if you have someone cycle the switch while you touch it. There is the chance the fan wheel fell off (this usually generates a racket) or a chipmunk has it packed with acorns. If you can't feel the motor start it is time to break out the meter and start probing.

It seems highly likely that it's the Blower Motor Speed Controller. It's a known problem on the last couple generations of this platform and a redesigned part has been issued (8W7Z-19E624-A). It's possible that it's just a bad blower motor, or both the blower motor and controller could be bad. Good info here. The blower motor and the controller are in the engine bay on the passenger side of the firewall. The blower motor connector should have power on the brown-orange wire. The orange-red wire is the ground. If they're both good, it's a bad blower motor. If there is no ground, it's time to check the controller. The darn thing is so hard to get to, though, you might as well just go ahead and replace it if the blower motor is good. Especially if the redesigned part has not already been installed. I don't think it was even available until 2009 or later. Replacing it involves clamping off the heater hoses it's under and getting them out of the way. It's held in by two 8mm screws. If you're incredibly lucky, persistent or perhaps gifted, you might be able to get it out without undoing the hoses, but the guy that's been doing this for years says he can't always do it without getting at least one of the hoses off. If you're determined to test it with a multimeter before swapping it, you can get at the connecter if you get the EVAP solenoid out of the way.